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Abstract:

A liquid phase process is disclosed for producing halogenated alkane
adducts of the formula CAR1R2CBR3R4 (where A, B,
R1, R2, R3, and R4 are as defined in the
specification) which involves contacting a corresponding halogenated
alkane, AB, with a corresponding olefin,
CR1R2═CR3R4 in a dinitrile or cyclic carbonate
ester solvent which divides the reaction mixture into two liquid phases
and in the presence of a catalyst system containing (i) at least one
catalyst selected from monovalent and divalent copper; and optionally
(ii) a promoter selected from aromatic or aliphatic heterocyclic
compounds which contain at least one carbon-nitrogen double bond in the
heterocyclic ring. When hydrochlorofluorocarbons are formed, the chlorine
content may be reduced by reacting the hydrochlorofluorocarbons with HF.
Azeotropes of CClF2CH2CF3 with HF and azeotropes of
CF3CH2CHF2 with HF are also disclosed; as are process for
producing such azeotropes.

Claims:

1.-12. (canceled)

13. A composition comprising: (a) from about 44 to 84 mole percent HF;
and (b) from about 56 to 16 mole percent CF3CH2CHF2; said
composition exhibiting a relative volatility of about 1 at a pressure
within the range of 5.5 kPa to 3850 kPa when the temperature is adjusted
within the range of -50.degree. C. to 130.degree. C.

14. The azeotrope of claim 13 produced by reacting CCl4 with
CH.sub.2.dbd.CHCl to produce CCl3CH2CHCl2 and reacting
said CCl3CH2CHCl2 with HF.

15.-20. (canceled)

21. A composition consisting essentially of: (a) Hydrogen fluoride; and
CF3CH2CHF2 in an amount effective to form an azeotropic
combination with hydrogen fluoride.

22. The azeotrope of claim 21 produced by reacting CCl4 with the
CH.sub.2.dbd.CHCl in a dinitrile or cyclic carbonate ester solvent which
divides the reaction mixture into two liquid phases, and in the presence
of a catalyst system containing (i) at least one catalyst selected from
the group consisting of monovalent and divalent copper and (ii) a
promoter selected from aromatic and aliphatic heterocyclic compounds
which contain at least one carbon-nitrogen double bond in the
heterocyclic ring, to produce CCl3CH2CHCl2, and reacting
said CCl3CH2CHCl2 with HF.

Description:

[0001] This application is a Divisional application of pending U.S. patent
application Ser. No. 11/809,485, filed May 31, 2007, which is a
Divisional application of U.S. patent application Ser. No. 10/956,672,
filed Oct. 1, 2004, which issued as U.S. Pat. No. 7,241,928, which is a
divisional of U.S. patent application Ser. No. 10/460,270, filed Jun. 12,
2003, which issued as U.S. Pat. No. 6,858,762 and which is a divisional
of U.S. patent application Ser. No. 09/638,549, filed Aug. 14, 2000,
which issued as U.S. Pat. No. 6,755,942, which is a divisional of U.S.
patent application Ser. No. 09/011,401, filed Jan. 28, 1998, which issued
as U.S. Pat. No. 6,291,730 and represents a national filing under 35 USC
371 of International Application No. PCT/US96/12547 filed Jul. 31, 1996,
and claims the priority benefit of U.S. Provisional Application Ser. No.
60/019,994 filed Jun. 18, 1996, U.S. Provisional Application Ser. No.
60/014,810 filed Apr.4, 1996 and U.S. Provisional Application Ser. No.
60/001,702 filed Aug. 1, 1995. All of which are incorporated by reference
herein.

FIELD OF THE INVENTION

[0002] This invention relates to the manufacture of halogenated alkanes
using the catalytic reaction of haloalkanes with halogenated olefins,
compounds produced thereby, azeotropic compositions which can be obtained
upon fluorination of such compounds, and use of azeotropes in separation
processes.

BACKGROUND

[0003] The catalyzed radical addition of haloalkanes to olefins is a well
known reaction. Typically, however, when a haloalkane (e.g., AB, where A
is a substituted carbon atom and B is a halogen other than fluorine) is
added to an olefin (e.g., CH2═CHR) to form the saturated adduct
(e.g., CH2ACHBR), the products (i.e., halogenated addition
compounds) also include varying amounts of telomers (e.g.,
A(CH2CHR)nB, where n is equal to 2 or more). For example,
Canadian Patent No. 2,073,533 discloses a process for the manufacture of
CCl3CH2CCl3 by reacting carbon tetrachloride with
vinylidene chloride using copper catalysts in acetonitrile. The
selectivity for CCl3CH2CCl3 with respect to converted
vinylidene chloride was 87%. It has been shown in the art that the major
by-product is the C5 telomer, CCl3(CH2CCl2)2Cl.
Furthermore, since the catalyzed addition of haloalkanes to olefins is
done in a homogeneous medium, separation of the catalyst from the product
can present difficulties. This is especially so when it is desired to run
the reaction in a continuous manner.

[0004] The halogenated adducts are useful intermediates for the production
of fluoroalkanes, particularly, hydrofluoroalkanes. These latter
compounds are useful as refrigerants, fire extinguishants, heat transfer
media, propellants, foaming agents, gaseous dielectrics, sterilant
carriers, polymerization media, particulate removal fluids, carrier
fluids, buffing abrasive agents, displacement drying agents and power
cycle working fluids. There is an interest in developing more efficient
processes for the manufacture of hydrofluoroalkanes.

SUMMARY OF THE INVENTION

[0005] A liquid phase process is provided in accordance with this
invention for producing halogenated alkane adducts of the formula
CAR1R2CBR3R4 wherein R1, R2, R3, and
R4 are each independently selected from the group consisting of H,
Br, Cl, F, C1-C6 alkyl, CN, CO2CH3, CH2Cl, and
aryl (e.g., phenyl), provided that when either R3 or R4 is
selected from the group consisting of C3-C6 alkyl, CN,
CO2CH3, CH2Cl, and aryl, then R1, R2, and the
other of R3 and R4 are H, and when R3 and R4 are
selected from the group consisting of Cl, F, CH3 and C2H5,
then R1 and R2 are H, and when either R1 or R2 and
either R3 or R4 are selected from the group consisting of Cl,
F, CH3 and C2H5, then the other of R1 and R2 and
the other of R3 and R4 are H; A is selected from the group
consisting of CX3, CH3-aXa,
CnH.sub.(2n+1)-bXb and CHcX2-cR, where R is
CnH.sub.(2n+1)-bXb (e.g., CF3 and CCl2CF3),
each X is independently selected from the group consisting of Br, F, Cl
and I, a is an integer from 0 to 3, n is an integer from 1 to 6, b is an
integer from 1 to 2n+1, and c is an integer from 0 to 1; and B is
selected from the group consisting of Br, Cl and I; provided that (1)
when A is CX3 then only one of X is I, (2) when A is
CH3-aXa, then each X is B and a is 2 when B is Br or Cl, and a
is an integer from 0 to 2 when B is I, and (3) when A is
CnH.sub.(2n+1)-bXb, then each X is independently selected
from Cl and F, and B is I. The process comprises contacting a halogenated
alkane of the formula AB (where A and B are as indicated above) with an
olefin of the formula CR1R2═CR3R4 (where R1,
R2, R3 and R4 are as indicated above) in a dinitrile or
cyclic carbonate ester solvent which divides the reaction mixture into
two liquid phases and in the presence of a catalyst system containing (i)
at least one catalyst selected from the group consisting of monovalent
and divalent copper; and optionally (ii) a promoter selected from the
group consisting of aromatic or aliphatic heterocyclic compounds which
contain at least one carbon-nitrogen double bond in the heterocyclic
ring.

[0006] This invention further provides a process for producing
hydrofluoro- alkanes (e.g., CF3CH2CHF2). This process
comprises (a) producing a halogenated alkane adduct (e.g.,
CCl3CH2CHCl2) by reacting AB (e.g., CCl4) and
CR1R2═CR3R4 (e.g., CH2═CHCl) as
indicated above (provided that R1, R2, R3 and R4 are
independently selected from H, CH3, C2H5, Cl and F, B and
X are Cl and at least one of AB and CR1R2 ═CR3R4
contains hydrogen), and (b) reacting the adduct produced in (a) with HF.

[0007] This invention also provides a process for the purification of at
least one compound of the formula
CA1R5R6CB1R7R8 from a mixture comprising HF
and said at least one compound, wherein Al is selected from the group
consisting of CH3-aX1a and CHcX12-cR9
where R9 is CnH.sub.(2n+1)-bX1b, each X1
and B1 is independently selected from the group consisting of Cl and
F, R5, R6, R7, and R8 are each independently selected
from the group consisting of H, Cl and F, and a, b, c and n are as
defined above, provided that at least one of A1, R5, R6,
R7, or R8 comprises hydrogen. The purification process
comprises (a) subjecting the mixture of HF and said at least one compound
to a distillation step in which a composition enriched in either (i) HF
or (ii) said at least one compound is removed as a first distillate with
the bottoms being enriched in the other of said components (i) or (ii);
(b) subjecting said first distillate to an additional distillation
conducted at a different pressure in which the component enriched as
bottoms in (a) is removed as a second distillate with the bottoms of the
additional distillation enriched in the component enriched in the first
distillate; and (c) recovering at least one compound of the formula
CA1R5R6CB1R7R8 essentially free of HF as
bottoms from either the distillation of (a) or the distillation of (b).

[0008] New compounds provided in accordance with this invention include
CF3CF2CCl2CH2CCl3,
CF3CCl2CH2CH2Cl and CF3CCl2CH2CHClF.
These compounds are useful as intermediates for producing
hydrofluorocarbons.

[0009] New compositions produced by this invention include azeotropic
compositions of CF3CH2CHF2 with HF and azeotropic
compositions of

[0010] CF3CH2CClF2 with HF. A composition comprising from
about 44 to 84 mole percent HF and from about 56 to 16 mole percent
CF3CH2CHF2 is provided which, when the temperature is
adjusted within the range of -50° C. to 130° C., exhibits a
relative volatility of about 1 at a pressure within the range of 5.5 kPa
to 3850 kPa. Also, a composition comprising from about 63.0 to 90.1 mole
percent HF and from about 37.0 to 9.9 mole percent
CF3CH2CClF2 is provided which, when the temperature is
adjusted within the range of -40° C. to 110° C., exhibits a
relative volatility of about 1 at a pressure within the range of about
9.3 kPa to 2194 kPa.

BRIEF DESCRIPTION OF THE DRAWING

[0011] FIG. 1 is a schematic flow diagram of an embodiment of the
purification process of this invention, namely, an azeotrope separation
process.

DETAILED DESCRIPTION

[0012] The present invention relates to the addition of halogenated
alkanes to unsaturated compounds to form an adduct. Specifically, this
invention relates to the addition of a halogenated alkane of the general
formula AB to an unsaturated compound CR1R2═CR3R4
to form a corresponding adduct CAR1R2CBR3R4 in the
presence of a copper catalyst (Cu.sup.+ and/or Cu.sup.++) in a suitable
solvent (a dinitrile or cyclic carbonate ester solvent). A promoter
containing a C═N ring bond may also be advantageously used.

[0013] The addition of saturated, halogenated alkanes to alkenes to form
adducts is known in the art. A wide range of saturated, halogenated
alkanes may be used in the process of the invention. Examples of suitable
saturated, halogenated alkanes are given by Walling and Huyser in Tables
V, VI, VII, and VIII in Chapter 3 of Organic Reactions, Vol. 13 (1963).

[0014] Halogenated alkanes, AB, that are particularly useful for the
process of this invention include certain compounds where A is selected
from the group consisting of CX3, CH3-aXa,
CnH.sub.(2n+1)-bXb and CHcX2-cR where each X is
Br, Cl or I and R is CnH.sub.(2n+1)-bXb (e.g., CF3
and CCl2CF3); and B is Br, F, Cl or I. Included are compounds
where A is CX3 and only one of X is I. Also included are compounds
where A is CH3-aXa where X is B and where when X is Br or Cl, a
is 2, and when X is I, a is an integer from 0 to 2. Also included the
compounds where A is CnH.sub.(2n+1)-bXb, where each X is
independently selected from Cl and F, n is an integer from 1 to 6, b is
an integer from 1 to 2n+1, and B is I. Also included are compounds where
A is CHcX2-cR wherein c is an integer from 0 to 1. Examples of
saturated, halogenated alkanes suitable for the process of this invention
include CCl4, CBrCl3, CCl2FCCl2F, CCl3CF3,
CCl3CF2CF3, CCl3CH2CCl3,
CCl3CH2CF3, CCl3CF2CClF2, CF3I,
CF3CF2I, CF3CFICF3 and CF3CF2CF2I.

[0015] A wide range of alkenes may be used in the process of the
invention. Examples of suitable alkenes are given by Walling and Huyser
in Tables V, VI, VII, and VIII in Chapter 3 of Organic Reactions, Vol. 13
(1963). Examples of alkenes suitable for the process of this invention
include CH2═CH2, CH2═CHCl, CH2═CHF,
CHCl═CHCl, CH2═CCl2, CH2═CF2,
CH2═CHCH3, CH2═CHCH2Cl, and
CH2═CHC6H5.

[0016] The addition of halogenated alkanes to alkenes to form the
corresponding adducts is catalyzed by copper compounds in the +1 or +2
oxidation state. Preferred copper compounds for the process of this
invention include copper(I) chloride, copper(II) chloride, copper(I)
bromide, copper(II) bromide, copper(I) iodide, copper(II)acetate and
copper(II) sulfate. The catalysts are preferably anhydrous; and
preferably, the addition is done under substantially anhydrous conditions
in the substantial absence of oxygen. Without wishing to be bound by
theory, it is believed that the effect of the catalyst is to enhance the
yield of the 1:1 addition product (i.e., the adduct) of the halogenated
alkanes to the alkene relative to higher molecular weight telomers that
are known in the art.

[0017] The copper catalyst for the process of the invention may, if
desired, be promoted by certain heterocyclic compounds. Suitable
promoters include those selected from the group consisting of imidazoles,
imidazolines, oxadiazoles, oxazoles, oxazolines, isoxazoles, thiazoles,
thiazolines, pyrrolines, pyridines, trihydropyrimidines, pyrazoles,
triazoles, triazolium salts, isothiazoles, tetrazoles, tetrazolium salts,
thiadiazoles, pyridazines, pyrazines, oxazines and dihydrooxazine.
Preferred promoters include those selected from the group having Formula
(I) or Formula (II) as follows:

##STR00001##

where E is selected from --O--, --S--, --Se--, --CH2-- and
--N(R8a)--; R5a is sel lected from the group consisting of
CH3 and C2H5 (and is preferably CH3); --R6a and
R7a are selected from the group consisting of H, CH3,
C6H5 (i.e., phenyl), CH2C6H5,
CH(CH3)2, and fused phenyl; L is selected from the group
consisting of --O--, --S--, --Se--, --N(R8a)--, --C6H4--,
2,6-pyridyl, --OC6H4-C6H4O--,
--CH2CH2OCH2CH2-- and --(CH2)p-- where p is
an integer from 0 to 6; and each R8a is selected from the group
consisting of H and CmH2m+1 where m is an integer from 1 to 6.
The bond between each pair of carbon atoms respectively attached to
--R6a and R7a (as represented by the dashed bond lines in
Formula (I) and Formula (II) can be either a single or a double bond. Of
note are compounds of Formula (II) which are optically active. Without
wishing to be bound by theory, it is believed that the effect of the
promoter is to enhance the rate and selectivity of the reaction.
Frequently, use of the promoter will enable operation of the reaction at
a lower temperature, and with an acceptable rate, than would be possible
in the absence of the promoter. Reference is made to U.S. Patent
Application Ser. No. 60/001,702, a priority document for PCT
International Publication No. 97/05090, which is hereby incorporated by
reference, for further disclosure relating to such promoters.

[0018] The process of this invention is carried out in the presence of a
solvent.

[0019] Typically, the solvents of this invention divide the reaction
mixture into two liquid phases. Suitable solvents for the process of the
invention thus include those which not only promote the formation of the
1:1 adduct, but also divide the reaction mixture into two liquid phases.
The product addition compound is preferably concentrated in the lower
liquid phase, while the solvent and catalyst are preferably concentrated
in the top liquid phase. Preferred solvents for the process of this
invention include dinitriles and cyclic carbonate esters. These solvents
are commercially available. Examples of solvents for the process of this
invention include ethylene carbonate, propylene carbonate, butylene
carbonate, 1,2-cyclohexane carbonate, malononitrile, succinonitrile,
ethyl succinonitrile, glutaronitrile, methyl glutaronitrile,
adiponitrile, pimelonitrile, suberonitrile, and mixtures thereof.
Preferred solvents for the process of the invention are adiponitrile,
glutaronitrile, methyl glutaronitrile, and propylene carbonate.

[0020] The choice of the solvent for the process of the invention will
require some experimentation, as the solubility characteristics of the
starting materials and adducts need to be considered to develop the
required two phase system. However, the preferred solvents noted above
provide the desired two phase systems for a number of addition reactions
as illustrated in the Examples.

[0021] Another important criterion for the choice of solvent is the
boiling point of the solvent relative to that of the desired addition
compounds. It is preferred that the boiling point of the solvent be
higher than the boiling point of the adduct so that easy separation of
the adduct from the solvent may be made by distillation.

[0022] Another important criterion for the choice of solvent is that it
serve as a solvent for the catalyst or catalyst/promoter mixture at the
reaction temperature or below.

[0023] The catalyst system comprising the copper compound and the solvent,
(and optionally the promoter when present as disclosed above) can be
prepared in advance in a suitable mixing vessel and then added to the
reaction mixture. Alternatively, the individual components of the
catalyst system can be added individually to the reactor.

[0024] The process of the present invention is suitably conducted at a
temperature in the range of from about 90° C. to 150° C.,
preferably from about 100° C. to about 140° C., and most
preferably, from about 110° C. to 130° C.

[0025] The pressure of the process is not critical and can be
subatmospheric, atmospheric or superatmospheric, preferably,
superatmospheric. The pressure in the system is frequently governed by
the vapor pressures of the reactants at the temperature of the reaction.
The reaction may be carried out under a pressure of nitrogen or other
inert gas diluent.

[0026] While the use of a copper catalyst tends to minimize the formation
of higher telomers as known in the art, the formation of 2:1 and higher
adducts (i.e., those addition compounds containing more than one mole of
alkene per mole of adduct) can be further controlled by manipulating
reaction variables such as the molar ratio of the halogenated alkane to
the alkene. Higher molar ratios of halogenated alkane to alkene and
dilution of the alkene reduce telomer formation. This can be accomplished
by continuously feeding the alkene or mixture of the alkene and of the
halogenated alkane to a heel of the halogenated alkane and catalyst
mixture.

[0027] The total amount of copper catalyst used in the reaction of this
invention is typically at least about 5 mmoles, preferably from about 5
mmole to 700 mmoles, and more preferably from about 10 mmoles to 100
mmoles, per mole of alkene used.

[0028] When used, the amount of optional promoter used in the reaction of
this invention is typically at least an amount sufficient to provide 2
mmol of heterocyclic ring which contains carbon-nitrogen double bonding
per mmol of copper catalyst. For example, typically at least about 2
moles of Formula (I) promoter or about 1 mole of Formula (II) promoter is
typically used per mole of copper catalyst.

[0029] The amount of halogenated alkane used in the reaction of this
invention is typically at least about 1 mole, and preferably from about 2
moles to 10 moles, per mole of alkene used.

[0030] The amount of solvent used in the reaction of this invention is
typically at least about 5 moles, and preferably from about 10 moles to
100 moles, per mole of copper catalyst used.

[0031] The process of the present invention facilitates easy separation of
the 1:1 addition product of the halogenated alkane to the alkene by
taking advantage of the two phase nature of reaction mixture of this
invention. That is, the desired 1:1 addition product tends to accumulate
in the lower of the two liquid layers while the solvent and the catalyst
tend to accumulate in the upper layer. The upper and lower layers may be
separated continuously in a separation zone (e.g., a decanter) as is
known in the art or on a batch basis by allowing the phases to separate
in the reactor and removing the lower layer from the bottom of the
vessel. The catalyst and solvent in the upper layer may be re-used for
subsequent reactions as illustrated in Examples 3, 4, and 5.

[0032] If the reaction is being operated in a continuous manner or if
multiple batches are being run with the same catalyst charge, a gradual
loss of reaction rate may be observed. A satisfactory reaction rate can
often be restored by addition of promoter to the reaction.

[0033] The desired addition product may be separated from any alkene
starting material, alkane starting material, solvent, and any higher
telomer products by conventional techniques such as distillation. The low
boiling fraction will typically be the starting halogenated alkane and
the alkene which may be recovered and recycled to the reactor. Higher
boiling material will comprise the solvent and any higher boiling telomer
by-products. The higher boiling phase may be further refined and the
solvent recycled to the reactor. The separation of the two liquid phases
in the reactor may be done at temperatures between the reaction
temperature and ambient temperature; cooling the reaction mixture lower
than room temperature is usually not necessary.

[0034] The reaction zone and its associated feed lines, effluent lines and
associated units should be constructed of materials resistant to
corrosion. Typical materials of construction include steel reactors lined
with poly(tetrafluoroethylene) or glass and glass reactors.

[0035] The addition compounds that comprise the products of this invention
are useful as intermediates for the formation of hydrofluoroalkanes.
(Novel compounds provided herein include
CF3CF2CCl2CH2CCl3, which may be made by reacting
CF3CF2CCl3 with CH2═CCl2;
CF3CCl2CH2CH2Cl, which may be made by reacting
CF3CCl3 with CH2═CH2 and
CF3CCl2CH2CHClF, which may be made by reacting
CF3CCl3 with CH2═CHF). These addition compounds can be
reacted with hydrogen fluoride in either the liquid or vapor phase in the
presence of a suitable fluorination catalyst.

[0036] In the liquid phase, the addition compounds can be reacted with HF
in the presence of catalysts selected from the halides of antimony,
molybdenum, niobium, tantalum, tin and titanium, and mixtures thereof,
preferably, antimony, niobium and tantalum. The temperature of the
reaction can be in the range of 50° C. to 175° C.,
preferably, 60° C. to 150° C. The pressure is selected so
that the the reaction medium is maintained in the liquid state, typically
between 101 kPa and 5000 kPa, preferably, 1135 kPa to 3203 kPa. For
example, 1,1,1,3,3,3-hexachloropropane (HCC-230fa) can be reacted with HF
in the liquid phase using halides, fluorosulfonates or triflates of
antimony, molybdenum, niobium, tantalum, tin or titanium, or mixtures
thereof as catalysts to produce 1,1,1,3,3,3-hexafluoropropane
(HFC-236fa). 1-Chloro-1,1,3,3,3-pentafluoropropane

[0037] (HCFC-235fa) can also be prepared from HCC-230fa (e.g., by reacting
said CCl3CH2CCl3 with HF). The reaction products may be
separated by conventional techniques such as distillation. Azeotropic
compositions of HCFC-235fa and HF can be produced in this manner; and the
HCFC-235fa can be further reacted with HF to produce HFC-236fa. The
HCFC-235fa product can also be hydrodechlorinated using a
hydrodehalogenation catalyst to produce 1,1,1,3,3-pentafluoropropane
(HFC-245fa). Palladium on acid-washed carbon is a preferred catalyst for
the conversion of HCFC-235fa to HFC-245fa.

[0038] In another embodiment of this invention carbon tetrachloride can be
reacted with vinyl chloride to produce the adduct
1,1,1,3,3-pentachloropropane (i.e., CCl3CH2CHCl2 or
HCC-240fa). CCl3CH2CHCl2 can then be reacted with HF
(e.g., in the liquid phase using the process described above) to produce
CF3CH2CHF2. The reaction products may be separated by
conventional techniques such as distillation. Azeotropic compositions of
HFC-245fa and HF can be produced in this manner.

[0039] In the vapor phase, the addition compounds can be reacted with HF
in the presence of catalysts comprising trivalent chomium. Catalysts
prepared by pyrolysis of (NH4)2Cr2O7 to produce
Cr2O3 and pretreated with HF and catalysts prepared by
pretreating Cr2O3 having a surface area greater than about 200
m2/g with HF are preferred. The temperature of the reaction can be
in the range of 200° C. to 400° C., preferably, 250°
C. to 375° C. The pressure is not critical and is selected so that
the reaction starting materials and products are maintained in the vapor
state at the operating temperature. For example, it has recently been
disclosed in U.S. Pat. No. 5,414,165 that 1,1,1,3,3,3-hexafluoropropane
may be prepared in high yield from 1,1,1,3,3,3-hexachloropropane by a
vapor phase hydrofluorination process in the presence of a trivalent
chromium catalyst.

[0040] Although the 1:1 addition compounds of the halogenated alkanes to
the alkenes are the preferred products, the 2:1 adducts may also be
useful.

[0041] Hydrofluorocarbons such as CF3CH2CHF2 and
hydrochlorofluorocarbons such as CF3CH2CClF2 form
azeotropes with HF; and conventional decantation/distillation may be
employed if further purification of the hydrofluorocarbons is desired.

[0042] Moreover, a process for purification as provided herein may also be
also be used. Hydrofluoroalkanes and chloro-precursors thereof provided
in the process for producing halogenated alkane adducts described above
and/or the process for producing hydrofluoroalkanes described above
include compounds of the formula
CA1R5R6CB1R7R8. Typically, these compounds
form azeotropes with HF, and the process for purification provided herein
may be advantageously used for purification of a compound of said formula
from its HF azeotrope (e.g., a binary azeotrope of a compound having the
formula CA1R5R6CB1R7R8 with HF). Examples
of compounds which can be purified from their binary azeotropes with HF
by this purification process include compounds selected from the group
consisting of CF3CH2CHF2, CF3CH2CF3,
CF3CH2CClF2, CHCl2CH2CF3,
CHClFCH2CClF2, CHClFCH2CF3, and
CHF2CH2CClF2.

[0043] An azeotrope is a liquid mixture that exhibits a maximum or minimum
boiling point relative to the boiling points of surrounding mixture
compositions. A characteristic of minimum boiling azeotropes is that the
bulk liquid composition is the same as the vapor compositions in
equilibrium therewith, and distillation is ineffective as a separation
technique. It has been found, for example, that CF3CH2CHF2
(HFC-245fa) and HF form a minimum boiling azeotrope. This azeotrope can
be produced as a co-product with HFC-245fa. As discussed further below,
compositions may be formed which consist essentially of azeotropic
combinations of hydrogen fluoride with HFC-245fa. These include a
composition consisting essentially of from about 44 to 84 mole percent HF
and from about 56 to 16 mole percent HFC-245fa (which forms an azeotrope
boiling at a temperature between -50° C. and about 130° C.
at a pressure between about 5.5 kPa and about 3850 kPa). In other words,
when the temperature is adjusted within the range of -50° C. to
130° C., these compositions exhibit a relative volatility of about
1 (e.g., between 0.9 and 1.1) at a pressure within the range of 5.5 kPa
to 3850 kPa. The hydrofluorocarbons (e.g., HFC-245fa) can be separated
from the HF in such azeotropes by conventional means such as
neutralization and decantation. However, azeotropic compositions of the
hydrofluorocarbons and HF (e.g., an azeotrope recovered by distillation
of hydrogenolysis reactor effluent) are useful as recycle to a
fluorination reactor, where the recycled HF can function as a reactant
and the recycled HFC-245fa can function to moderate the temperature
effect of the heat of reaction. It will also be apparent to one of
ordinary skill in the art that distillation including azeotropes with HF
can typically be run under more convenient conditions than distillation
without HF (e.g., where HF is removed prior to distillation).

[0044] It has also been found that CClF2CH2CF3 (HCFC-235fa)
and HF form a minimum boiling azeotrope. This azeotrope can be produced
as a co-product with HCFC-235fa. As discussed further below, compositions
may be formed which consist essentially of azeotropic combinations of
hydrogen fluoride with HCFC-235fa. These include a composition consisting
essentially of from about 63.0 to 90.1 mole percent HF and from about
37.0 to 9.9 mole percent HCFC-235fa (which forms an azeotrope boiling at
a temperature between -40° C. and about 110° C. at a
pressure between about 9.3 kPa and about 2194 kPa). In other words, when
the temperature is adjusted within the range of -40° C. to
110° C., these compositions exhibit a relative volatility of about
1 (e.g., between 0.9 and 1.1) at a pressure within the range of about 9.3
kPa to 2194 kPa. The hydrofluorocarbons (e.g., HCFC-235fa) can be
separated from the HF in such azeotropes by conventional means such as
neutralization and decantation. However, azeotropic compositions of the
hydrofluorocarbons and HF (e.g., an azeotrope recovered by distillation
of hydrogenolysis reactor effluent) are useful as recycle to a
fluorination reactor, where the recycled HF can function as a reactant
and the recycled HCFC-235fa can further react to provide HFC-236fa and
can function to moderate the temperature effect of the heat of reaction.
It will also be apparent to one of ordinary skill in the art that
distillation including azeotropes with HF can typically be run under more
convenient conditions than distillation without HF (e.g., where HF is
removed prior to distillation).

HFC-245fa/HF Azeotrope

[0045] As noted above, the present invention provides a composition which
consists essentially of hydrogen fluoride and an effective amount of a
CF3CH2CHF2 to form an azeotropic combination with hydrogen
fluoride. By effective amount is meant an amount which, when combined
with HF, results in the formation of an azeotrope or azeotrope-like
mixture. As recognized in the art, an azeotrope or an azeotrope-like
composition is an admixture of two or more different components which,
when in liquid form under given pressure, will boil at a substantially
constant temperature, which temperature may be higher or lower than the
boiling temperatures of the individual components, and which will provide
a vapor composition essentially identical to the liquid composition
undergoing boiling.

[0046] For the purpose of this discussion, azeotrope-like composition
means a composition which behaves like an azeotrope (i.e., has
constant-boiling characteristics or a tendency not to fractionate upon
boiling or evaporation). Thus, the composition of the vapor formed during
boiling or evaporation of such compositions is the same as or
substantially the same as the original liquid composition. Hence, during
boiling or evaporation, the liquid composition, if it changes at all,
changes only to a minimal or negligible extent. This is to be contrasted
with non-azeotrope-like compositions in which during boiling or
evaporation, the liquid composition changes to a substantial degree.

[0047] Accordingly, the essential features of an azeotrope or an
azeotrope-like composition are that at a given pressure, the boiling
point of the liquid composition is fixed and that the composition of the
vapor above the boiling composition is essentially that of the boiling
liquid composition (i.e., no fractionation of the components of the
liquid composition takes place). It is also recognized in the art that
both the boiling point and the weight percentages of each component of
the azeotropic composition may change when the azeotrope or
azeotrope-like liquid composition is subjected to boiling at different
pressures. Thus an azeotrope or an azeotrope-like composition may be
defined in terms of the unique relationship that exists among components
or in terms of the compositional ranges of the components or in terms of
exact weight percentages of each component of the composition
characterized by a fixed boiling point at a specified pressure. It is
also recognized in the art that various azeotropic compositions
(including their boiling points at particular pressures) may be
calculated (see, e.g., W. Schotte, Ind. Eng. Chem. Process Des. Dev.
1980, 19, pp 432-439). Experimental identification of azeotropic
compositions involving the same components may be used to confirm the
accuracy of such calculations and/or to modify the calculations for
azeotropic compositions at the same or other temperatures and pressures.

[0048] It has been found that azeotropes of HF and HFC-245fa are formed at
a variety of temperatures and pressures. At a pressure of 7.60 psia (52.4
kPa) and -10° C., the azeotrope vapor composition was found to be
about 74.0 mole percent HF and about 26.0 mole percent HFC-245fa. At a
pressure of 26.7 psia (184 kPa) and 20° C., the azeotrope vapor
composition was found to be about 66.1 mole percent HF and 33.9 mole
percent HFC-245fa. Based upon the above findings, it has been calculated
that an azeotropic composition of about 84.4 mole percent HF and about
15.6 mole percent HFC-245fa can be formed at -50° C. and 0.80 psia
(5.5 kPa) and an azeotropic composition of about 44.1 mole percent HF and
about 55.9 mole percent HFC-245fa can be formed at 130° C. and 559
psia (3853 kPa). Accordingly, the present invention provides an azeotrope
or azeotrope-like composition consisting essentially of from about 84.4
to 44.1 mole percent HF and from about 15.6 to 55.9 mole percent
HFC-245fa, said composition having a boiling point from about -50°
C. at 5.5 kPa to about 130° C. at 3853 kPa.

HCFC-235fa/HF Azeotrope

[0049] It has been found that azeotropes of HF and HCFC-235fa are formed
at a variety of temperatures and pressures. At a pressure of 33.6 psia
(232 kPa) and 30° C., the azeotrope vapor composition was found to
be about 78.4 mole percent HF and about 21.6 mole percent HCFC-235fa. At
a pressure of 87.1 psia (600 kPa) and 60° C., the azeotrope vapor
composition was found to be about 72.4 mole percent HF and 27.6 mole
percent HCFC-235fa. Based upon the above findings, it has been calculated
that an azeotropic composition of about 90.1 mole percent HF and about
9.9 mole percent HCFC-235fa can be formed at -40° C. and 1.36 psia
(9.4 kPa) and an azeotropic composition of about 63.0 mole percent HF and
about 37.0 mole percent HCFC-235fa can be formed at 110° C. and
318 psia (2192 kPa). Accordingly, the present invention provides an
azeotrope or azeotrope-like composition consisting essentially of from
about 90.1 to 63.0 mole percent HF and from about 9.9 to 37.0 mole
percent HCFC-235fa, said composition having a boiling point from about
-40° C. at 9.4 kPa to about 110° C. at 2192 kPa.
intermediates.

[0050] The present invention also provides a process for the separation of
an azeotropic mixture of hydrogen fluoride (HF) and
1,1,1,3,3-pentafluoropropane (i.e., CF3CH2CHF2 or
HFC-245fa) to obtain CF3CH2CHF2 essentially free of HF.
For example, (a) an initial mixture wherein the molar ratio of HF to
HFC-245fa is greater than about 1.2:1 can be separated by azeotropic
distillation in a first distillation column wherein the temperature of
the feed inlet to said distillation column is about 97.3° C. and
the pressure is about 166.1 psia (1145 kPa), with azeotrope products
containing HF and HFC-245fa being removed as distillate from the top of
the first distillation column and any high boilers and HF being removed
from the bottom of the first distillation column; (b) said azeotrope
products from the top of the column in step (a) can be fed to a second
distillation column wherein the temperature of the feed inlet to said
second distillation column is about 19° C. and the pressure is
about 21.2 psia (146 kPa), with azeotrope products containing HF and
HFC-245fa being removed as distillate from the top of the second
distillation column; and (c) essentially pure HFC-245fa can be recovered
from the bottom of the second distillation column in step (b).
Optionally, said azeotrope products containing HF and HFC-245fa removed
from the top of the second distillation column can be recycled as feed to
step (a).

[0051] In another embodiment of this invention, (a) an initial mixture
wherein the molar ratio of HF to HFC-245fa is about 1.2:1 or less, can be
separated by azeotropic distillation in a first distillation column
wherein the temperature of the feed inlet to said distillation column is
about 19° C. and the pressure is about 21.2 psia (146 kPa) with
azeotrope products containing HF and HFC-245fa being removed as
distillate from the top of the first distillation column; (b) said
azeotrope products from the top of the column in step (a) can be fed to a
second distillation column wherein the temperature of the feed inlet to
said second distillation column is about 97.3° C. and the pressure
is about 166.1 psia (1145 kPa), with azeotrope products containing HF and
HFC-245fa being removed as distillate from the top of the second
distillation column and any high boilers and HF being removed from the
bottom of the second distillation column; and (c) essentially pure
HFC-245fa can be recovered from the bottom of the first distillation
column. Optionally, said azeotrope products containing HF and HFC-245fa
from the top of the second distillation column can be recycled as feed to
step (a).

[0052] The above embodiment of this invention involves azeotropic
distillation of mixtures of HF and CF3CH2CHF2 (HFC-245fa).
The product mixtures distilled in accordance with this invention can be
obtained from a variety of sources. These sources include product
mixtures from the following sequence of reactions.

[0053] CCl3CH2CHCl2 (HCC-240fa), a compound known in the
art, can be prepared from the reaction of carbon tetrachloride with vinyl
chloride as disclosed in U.S. Pat. No. 3,651,019. HCC-240fa can then be
reacted with HF in the vapor or liquid phase to afford HFC-245fa. The
fluorination reactor products typically include CHCl═CHCF3
(HCFC-1233zd), CHCl2CH2CF3 (HCFC-243fa),
CHClFCH2CClF2 (HCFC-243fb), CHClFCH2CF3 (HCFC-244fa),
CHF2CH2CClF2 (HCFC-244fb), CF3CH2CHF2
(HFC-245fa), HCl and HF. HCFC-243fa, HCFC-243fb, HCFC-244fa and
HCFC-244fb likely form azeotropes with HF.

[0054] While the initial mixture treated in accordance with the present
invention can be obtained from a variety of sources, an advantageous use
of the instant invention resides in treating the effluent mixtures from
the preparation of HFC-245fa as described above. Generally the reaction
effuents have a molar ratio of HF:HFC-245fa from about 0.1:1 to 100:1.
The preferred HF:HFC-245fa molar ratio is from about 1:1 to about 10:1
for vapor phase reactions and about 1:1 to about 50:1 for liquid phase
reactions to achieve maximum benefit from the instant process. When the
initial mixture treated in accordance with the invention also contains
HCl and possibly other low-boilers , the HCl and other low-boilers are
typically removed in another distillation column before feeding the
mixture to the azeotrope separation columns.

[0055] High-boilers, if present, can be removed in an independent
distillation column after separation of the HF from the HFC-245fa.

[0056] FIG. 1 is illustrative of one method of practicing this invention.
Referring to FIG. 1, a feed mixture derived from an HFC-245fa synthesis
reactor comprising HF and HFC-245fa, wherein the molar ratio of
HF:HFC-245fa is greater than about 1.2:1, from an HCl removal column (not
shown), is passed through line (426) to a multiple stage distillation
column (410), operating at a temperature of about 75° C. and a
pressure of about 1135 kPa. The bottoms of the distillation column (410),
which contains HF at a temperature of about 104° C. and a pressure
of about 1156 kPa is removed through line (436) and can be recycled back
to the HFC-245fa synthesis reactor. The distillate from column (410)
which contains HF/HFC-245fa azeotrope (HF:HFC-245fa molar ratio is about
1.2:1) is removed from the top of the column (410) and sent through line
(435) to column (420). The distillate from column (420) which contains
HF/HFC-245fa azeotrope (HF:HFC-245fa molar ratio is about 2.1:1) and is
at a temperature of about 12° C. and a pressure of about 136 kPa
is removed from the top of column (420) and is recycled through line
(445) to column (410). The bottoms of the distillation column (420) which
contains essentially pure HFC-245fa at about 26.5° C. and 156 kPa
is removed from the bottom of column (420) through line (446). In this
embodiment, column (410) operates as a high pressure column. Column (420)
operates as a low pressure column.

[0057] In another embodiment of this invention the pressures of the
columns are reversed. Again referring to FIG. 1, a feed mixture derived
from an HFC-245fa synthesis reactor comprising HF and HFC-245fa, wherein
the molar ratio of HF:HFC-245fa is about 1.2:1 or less, from an HCl
removal column (not shown), is passed through line (426) to a multiple
stage distillation column (410), operating at a temperature of about
12° C. and a pressure of about 136 kPa. The bottoms of the
distillation column (410) which contains essentially pure HFC-245fa at
about 28.5° C. and 156 kPa is removed from the bottom of column
(410) through line (436). The distillate from column (410) which contains
HF/HFC-245fa azeotrope (HF:HFC-245fa molar ratio is about 2.1:1) at a
temperature of about 12° C. and a pressure of about 140 kPa is
removed from the top of column (410) and sent through line (435) to
column (420). The distillate from column (420) which contains
HF/HFC-245fa azeotrope (HF:HFC-245fa molar ratio is about 1.2:1) and is
at a temperature of about 79° C. and a pressure of about 1135 kPa
is removed from the top of column (420) and is recycled through line
(445) to column (410). The bottoms of the distillation column (420) which
contains HF a temperature of about 104° C. and a pressure of about
1156 kPa is removed through line (446) and can be recycled back to the
HFC-245fa synthesis reactor. In this embodiment column (410) operates as
a low pressure column. Column (420) operates as a high pressure column.

[0058] While specific temperatures, pressures and molar ratios were
recited in the above two embodiments, variation of the pressure will also
cause shifts in the HF:HFC-245fa molar ratios and in the distillation
temperatures. The use of a "low" and a "high" pressure column in tandem
as described above can be used to separate HF from HFC-245fa for any
HF:HFC-245fa ratio (e.g., from 0.1:1 to 100:1).

[0059] The present invention further provides a process for the separation
an azeotropic mixture of hydrogen fluoride (HF) and
1,1,1,3,3-pentafluoro-3-chloropropane (i.e., CF3CH2CClF2
or HFC-235fa) to obtain CF3CH2CClF2 essentially free of
HF. For example, (a) an initial mixture wherein the molar ratio of HF to
HFC-235fa is greater than about 2:1 can be separated by azeotropic
distillation in a first distillation column wherein the temperature of
the feed inlet to said distillation column is about 109° C. and
the pressure is about 216.2 psia (1490 kPa), with azeotrope products
containing HF and HFC-235fa being removed as distillate from the top of
the first distillation column and any high boilers and HF being removed
from the bottom of the first distillation column; (b) said azeotrope
products from the top of the column in step (a) can be fed to a second
distillation column wherein the temperature of the feed inlet to said
second distillation column is about 29° C. and the pressure is
about 21.2 psia (146 kPa), with azeotrope products containing HF and
HFC-235fa being removed as distillate from the top of the second
distillation column; and (c) essentially pure HFC-235fa can be recovered
from the bottom of the second distillation column in step (b).
Optionally, said azeotrope products containing HF and HFC-235fa removed
from the top of the second distillation column can be recycled as feed to
step (a).

[0060] In another embodiment of this invention, (a) an initial mixture
wherein the molar ratio of HF to HFC-235fa is about 4:1 or less, can be
separated by azeotropic distillation in a first distillation column
wherein the temperature of the feed inlet to said distillation column is
about 28° C. and the pressure is about 21.2 psia (146 kPa) with
azeotrope products containing HF and HFC-235fa being removed as
distillate from the top of the first distillation column; (b) said
azeotrope products from the top of the column in step (a) can be fed to a
second distillation column wherein the temperature of the feed inlet to
said second distillation column is about 110° C. and the pressure
is about 216.2 psia (1490 kPa), with azeotrope products containing HF and
HFC-235fa being removed as distillate from the top of the second
distillation column and any high boilers and HF being removed from the
bottom of the second distillation column; and (c) essentially pure
HFC-235fa can be recovered from the bottom of the first distillation
column. Optionally, said azeotrope products containing HF and HFC-235fa
from the top of the second distillation column can be recycled as feed to
step (a).

[0061] The initial mixture of HF and HFC-235fa treated in accordance with
the present invention can be obtained from a variety of sources.
Generally the reaction effuents have a molar ratio of HF:HFC-235fa from
about 0.1:1 to 100:1. The preferred HF:HFC-235fa molar ratio is from
about 0.1:1 to about 10:1 for vapor phase reactions and about 1:1 to
about 50:1 for liquid phase reactions to achieve maximum benefit from the
instant process. When the initial mixture treated in accordance with the
invention also contains HCl and possibly other low-boilers , the HCl and
other low-boilers are typically removed in another distillation column
before feeding the mixture to the azeotrope separation columns.

[0062] High-boilers, if present, can be removed in an independent
distillation column after separation of the HF from the HFC-235fa.

[0063] FIG. 1 is again illustrative of one method of practicing this
invention. Referring to FIG. 1, a feed mixture derived from an HFC-235fa
synthesis reactor comprising HF and HFC-235fa, wherein the molar ratio of
HF:HFC-235fa is greater than about 2:1, from an HCl removal column (not
shown), is passed through line (426) to a multiple stage distillation
column (410), operating at a temperature of about 109° C. and a
pressure of about 1490 kPa. The bottoms of the distillation column (410),
which contains HF at a temperature of about 116° C. and a pressure
of about 1500 kPa is removed through line (436) and can be recycled back
to the HFC-235fa synthesis reactor. The distillate from column (410)
which contains HF/HFC-235fa azeotrope (HF:HFC-235fa molar ratio is about
2:1) is removed from the top of the column (410) and sent through line
(435) to column (420). The distillate from column (420) which contains

[0064] HF/HFC-235fa azeotrope (HF:HFC-235fa molar ratio is about 4:1) and
is at a temperature of about 15° C. and a pressure of about 136
kPa is removed from the top of the column (420) and is recycled through
line (445) to column (410). The bottoms of the distillation column (420)
which contains essentially pure HFC-235fa at about 41 ° C. and 156
kPa is removed from the bottom of column (420) through line (446). In
this embodiment, column (410) operates as a high pressure column. Column
(420) operates as a low pressure column.

[0065] In another embodiment of this invention the pressures of the
columns are reversed. Again referring to FIG. 1, a feed mixture derived
from an HFC-235fa synthesis reactor comprising HF and HFC-235fa, wherein
the molar ratio of HF:HFC-235fa is about 4:1 or less, from an HCl removal
column (not shown), is passed through line (426) to a multiple stage
distillation column (410), operating at a temperature of about 29°
C. and a pressure of about 146 kPa. The bottoms of the distillation
column (410) which contains essentially pure HFC-235fa at about 41
° C. and 156 kPa is removed from the bottom of column (410)
through line (436). The distillate from column (410) which contains
HF/HFC-235fa azeotrope (HF:HFC-235fa molar ratio is about 4:1) at a
temperature of about 16° C. and a pressure of about 136 kPa is
removed from the top of column (410) and sent through line (435) to
column (420). The distillate from column (420) which contains
HF/HFC-235fa azeotrope (HF:HFC-235fa molar ratio is about 2:1) and is at
at a temperature of about 94° C. and a pressure of about 1450 kPa
is removed from the top of column (420) and is recycled through line
(445) to column (410). The bottoms of the distillation column (420) which
contains HF at a temperature of about 116° C. and a pressure of
about 1500 kPa is removed through line (446) and can be recycled back to
the HFC-235fa synthesis reactor. In this embodiment column (410) operates
as a low pressure column. Column (420) operates as a high pressure
column.

[0066] While specific temperatures, pressures and molar ratios were
recited in the above two embodiments, variation of the pressure will also
cause shifts in the HF:HFC-235fa molar ratios and in the distillation
temperatures. The use of a "low" and a "high" pressure column in tandem
as described above can be used to separate HF from HFC-235fa for any
HF:HFC-235fa ratio, e.g., 0.1:1 to 100:1.

[0067] The present invention further provides a process for the separation
of an azeotropic mixture of hydrogen fluoride (HF) and
1,1,1,3,3,3-hexafluoropropane (i.e., CF3CH2CF3 or
HFC-236fa) to obtain CF3CH2CF3 essentially free of HF. For
example, (a) an initial mixture wherein the molar ratio of HF to
HFC-236fa is greater than about 0.85:1 can be separated by azeotropic
distillation in a first distillation column wherein the temperature of
the feed inlet to said distillation column is about 128° C. and
the pressure is about 366.2 psia (2524 kPa), with azeotrope products
containing HF and HFC-236fa being removed as distillate from the top of
the first distillation column and any high boilers and HF being removed
from the bottom of the first distillation column; (b) said azeotrope
products from the top of the column in step (a) can be fed to a second
distillation column wherein the temperature of the feed inlet to said
second distillation column is about 4.7° C. and the pressure is
about 21.2 psia (146 kPa), with azeotrope products containing HF and
HFC-236fa being removed as distillate from the top of the second
distillation column; and (c) essentially pure HFC-236fa can be recovered
from the bottom of the second distillation column in step (b).
Optionally, said azeotrope products containing HF and HFC-236fa removed
from the top of the second distillation column can be recycled as feed to
step (a).

[0068] In another embodiment of this invention, (a) an initial mixture
wherein the molar ratio of HF to HFC-236fa is less than about 1.18:1, can
be separated by azeotropic distillation in a first distillation column
wherein the temperature of the feed inlet to said distillation column is
about 4.3° C. and the pressure is about 21.2 psia (146 kPa) with
azeotrope products containing HF and HFC-236fa being removed as
distillate from the top of the first distillation column; (b) essentially
pure HFC-236fa can be recovered from the bottom of the first distillation
column; and (c) said azeotrope products from the top of the column in
step (a) can be fed to a second distillation column wherein the
temperature of the feed inlet to said second distillation column is about
127.9° C. and the pressure is about 364.7 psia (2514 kPa), with
azeotrope products containing HF and HFC-236fa being removed as
distillate from the top of the second distillation column and any high
boilers and HF being removed from the bottom of the second distillation
column. Optionally, said azeotrope products containing HF and HFC-236fa
from the top of the second distillation column can be recycled as feed to
step (a).

[0069] The initial mixture of HF and HFC-236fa treated in accordance with
the present invention can be obtained from a variety of sources.
Generally, the reaction effuents have a molar ratio of HF:HFC-236fa from
about 0.1:1 to 100:1. The preferred HF:HFC-236fa molar ratio is from
about 0.1:1 to about 10:1 for vapor phase reactions and about 1:1 to
about 50:1 for liquid phase reactions to achieve maximum benefit from the
instant process. When the initial mixture treated in accordance with the
invention also contains HCl and possibly other low-boilers, the HCl and
other low-boilers are typically removed in another distillation column
before feeding the mixture to the azeotrope separation columns.

[0070] High-boilers, if present, can be removed in an independent
distillation column after separation of the HF from the HFC-236fa.

[0071] FIG. 1 is again illustrative of one method of practicing this
invention. Referring to FIG. 1, a feed mixture derived from an HFC-236fa
synthesis reactor comprising HF and HFC-236fa, wherein the molar ratio of
HF:HFC-236fa is greater than about 0.85:1, from an HCl removal column
(not shown), is passed through line (426) to a multiple stage
distillation column (410), operating at a temperature of about
127.9° C. and a pressure of about 2514 kPa. The bottoms of the
distillation column (410), which contains HF at a temperature of about
140° C. and a pressure of about 2535 kPa is removed through line
(436) and can be recycled back to the HFC-236fa synthesis reactor. The
distillate from column (410) which contains HF/HFC-236fa azeotrope
(HF:HFC-236fa molar ratio is about 0.85:1) is removed from the top of the
column (410) and sent through line (435) to column (420). The distillate
from column (420) which contains HF/HFC-236fa azeotrope (HF:HFC-236fa
molar ratio is about 1.18:1) and is at a temperature of about
-0.4° C. and a pressure of about 136 kPa is removed from the top
of the column (420) and is recycled through line (445) to column (410).
The bottoms of the distillation column (420) which contains essentially
pure HFC-236fa at about 9.5° C. and 156 kPa is removed from the
bottom of column (420) through line (446). In this embodiment, column
(410) operates as a high pressure column. Column (420) operates as a low
pressure column.

[0072] In another embodiment of this invention the pressures of the
columns are reversed. Again referred to FIG. 1, a feed mixture derived
from an HFC-236fa synthesis reactor comprising HF and HFC-236fa, wherein
the molar ratio of HF:HFC-236fa is about 1.18:1 or less, from an HCl
removal column (not shown), is passed through line (426) to a multiple
stage distillation column (410), operating at a temperature of about
4.3° C. and a pressure of about 146 kPa. The bottoms of the
distillation column (410) which contains essentially pure HFC-236fa is
about 9.5° C. and 156 kPa is removed from the bottom of column
(410) through line (436). The distillate from column (410) which contains
HF/HFC-236fa azeotrope (HF:HFC-236fa molar ratio is about 1.18:1) at a
temperature of about -0.4° C. and a pressure of about 136 kPa is
removed from the top of column (410) and sent through line (435) to
column (420). The distillate from column (420) which contains
HF/HFC-236fa azeotrope (HF:HFC-236fa molar ratio is about 0.85:1) and is
at a temperature of about 96.7° C. and a pressure of about 2514
kPa is removed from the top of column (420) and is recycled through line
(445) to column (410). The bottoms of the distillation column (420) which
contains HF at a temperature of about 140° C. and a pressure of
about 2535 kPa is removed through line (446) and can be recycled back to
the HFC-236fa synthesis reactor. In this embodiment column (410) operates
as a low pressure column. Column (420) operates as a high pressure
column.

[0073] While specific temperatures, pressures and molar ratios were
recited in the above two embodiments, variation of the pressure will also
cause shifts in the HF:HFC-236fa molar ratios and in the distillation
temperatures. The use of a "low" and a "high" pressure column in tandem
as described above can be used to separate HF from HFC-236fa for any
HF:HFC-236fa ratio, e.g., 0.1:1 to 100:1.

[0074] Those skilled in the art will recognize that since the drawings are
representational, it will be necessary to include further items of
equipment in an actual commercial plant, such as pressure and temperature
sensors, pressure relief and control valves, compressors, pumps, storage
tanks and the like. The provision of such ancillary items of equipment
would be in accordance with conventional chemical engineering practice.

[0075] The distillation equipment and its associated feed lines, effluent
lines and associated units should be constructed of materials resistant
to hydrogen fluoride, hydrogen chloride and chlorine. Typical materials
of construction, well- known to the fluorination art, include stainless
steels, in particular of the austenitic type, and the well-known high
nickel alloys, such as Monel® nickel- copper alloys, Hastelloy®
nickel-based alloys and, Inconel® nickel-chromium alloys. Also
suitable for reactor fabrication are such polymeric plastics as
polytrifluorochloroethylene and polytetrafluoroethylene, generally used
as linings.

[0076] Without further elaboration, it is believed that one skilled in the
art can, using the preceding description, utilize the present invention
to its fullest extent. The following preferred specific embodiments are,
therefore, to be construed as merely illustrative, and does not constrain
the remainder of the disclosure in any way whatsoever.

EXAMPLES

[0077] Legend: [0078] ADN is CN(CH2)4CN AN is CH3CN
[0079] EOAz is 2-ethyl-2-oxazoline VCl2 is CH2═CCl2[0080] 230fa is CCl3CH2CCl3 450jfaf is
CCl3CH2CCl2CH2CCl3[0081] 245fa is
CF3CH2CHF2[0082] The C3H3ClF4 isomers are
CHClFCH2CF3 and CHF2CH2CClF2. [0083] The
C3H3Cl2F3 isomers are CHCl2CH2CF3 and
CHClFCH2CClF2.

General Comments

[0084] Unless otherwise indicated, the catalyst was CuCl2. When
2-ethyloxazoline was used as an additive, the molar ratio of additive to
catalyst was 2:1. The molar ratio of 230fa:450jfaf is reported as the
C3:C5 ratio.

Example 1

[0085] CCl4+CH2═CCl2→CCl3CH2CCl3

[0086] A 400 mL Hastelloy® C nickel alloy shaker tube was charged with
anhydrous cupric chloride (2.18 g, 0.0162 mole), adiponitrile (82.7 g,
0.765 mole), 2-ethyloxazoline (3.2 g, 0.0322 mole), carbon tetrachloride
(133.4 g, 0.867 mole), and vinylidene chloride (28.0 g, 0.289 mole). The
tube was sealed, cooled in a dry ice bath, evacuated, and purged with
nitrogen several times. The tube was placed in a heating jacket and
agitation begun. The tube was heated to 120° C. over the course of
an hour and then held at 117-120° C. for 0.9 hour; during this
time the pressure rose to 59 psig (508 kPa) and then dropped to 56 psig
(487 kPa). The tube was then cooled to ambient temperature.

[0087] The tube was discharged to afford 236.9 g of a product consisting
of a dark red brown liquid layer over a clear yellow supernatant. The top
layer (168.7 g) was filtered to yield 1.03 of solid. The filtrate from
the top layer and the yellow bottom layer were analyzed by gas
chromatography and found to have the compositions (in grams) indicated in
Table 1 below.

[0089] The reaction procedure was similar to that of Example 1. For runs 1
and 5 to 16, 0.29 moles of vinylidene chloride were charged to the shaker
tube. For run 2, 0.09 moles and for runs 3 and 4, 0.58 moles of
vinylidene chloride were charged to the shaker tube. For all the runs,
0.87 moles of carbon tetrachloride were used. For run 2, 0.0578 moles of
catalyst were used; for all the other runs, 0.0162 moles of catalyst were
used. For run 4, the catalyst was cuprous chloride, for all the other
runs it was cupric chloride. For runs 5 to 8 and 13 and 14, 44 mL of ADN
were charged to the shaker tube; for all the other runs, 87 mL of ADN
were used. For runs 3, 4 and 13 to 16, 0.0323 moles of an additive
(2-ethyloxazoline) were added to the shaker tube. The ratio of the
additive to copper was 2:1. The results using different conditions are
shown in Table 2.

[0090] A 600 mL Hastelloy® C nickel alloy, mechanically stirred,
autoclave was charged with 2.42 g (0.0180 mole) of CuCl2 and 1.78 g
(0.0180 mole) of CuCl. The autoclave was sealed and leak tested with 200
psig (1480 kPa) nitrogen. The pressure was then vented, the autoclave
evacuated, and charged with a mixture consisting of CCl4 (312.1 g,
2.029 moles), adiponitrile (124.6 g, 1.152 moles), CH2═CCl2
(9.81 g, 0.1012 mole), and 2-ethyl oxazoline (7.00 g, 0.0706 mole) from a
pressurized cylinder. The pressure of the autoclave was adjusted to 0
psig (101 kPa) with nitrogen and stirring set at 500 rpm. The contents of
the autoclave were heated to 119-120° C. for 0.5 hour and then
vinylidene chloride was fed to the reactor at a rate of 16 mL per hour
for 2.5 hour (48.4 g, 0.499 mole) at 120° C.; during this time the
pressure rose to 28 psig (294 kPa). The vinylidene chloride feed was shut
off and the autoclave held at 120° C. for another hour; the final
pressure was 25 psig (274 kPa). The reactor was cooled to ambient
temperature and the bottom layer in the autoclave was discharged via a
dip leg (248.1 g); the discharged solution consisted of a yellow liquid
with a small amount of a dark layer on top.

[0091] The autoclave was then recharged with carbon tetrachloride (240.0
g, 1.56 mole). The autoclave was heated to 120° C. and the
vinylidene chloride feed resumed at 16 mL/hr for 2 h; the pressure rose
from 28 (294 kPa) to 35 psig (343 kPa). The lower layer was discharged
from the reactor as above to afford 283.2 g of product.

[0092] In the same manner CCl4 was added three more times to the
autoclave (225.6 g, 231.6 g, and 229.4 g) with the bottom layer from the
autoclave discharged between additions (271.0 g, 280.5 g, 204.0 g,
respectively). The total amount of vinylidene chloride fed was 2.20
moles. The top layers from the autoclave were combined to give 259.4 g
and 2.3 of solid. The overall yield of 1,1,1,3,3,3-hexachloropropane was
about 89.5% with a vinylidene chloride conversion of 86.4%; the overall
ratio of 1,1,1,3,3,3-hexachloropropane to
1,1,1,3,3,5,5,5-octachloropentane was about 18.5.

[0093] The five bottom layers and the combined top layers from the reactor
were analyzed by a calibrated gas chromatograph. The weights of the
primary solution components are given below.

[0094] Following a procedure similar to that of Example 3, a 600 mL
HasteHoy--C nickel alloy, mechanically stirred, autoclave was charged
with 2.42 g (0.0180 mole) of CuCl2 and 1.78 g (0.0180 mole) of CuCl.
The autoclave was sealed and then charged with a mixture consisting of
CCl4 (309.1 g, 2.01 moles), adiponitrile (189.3 g, 1.75 moles), and
CH2═CCl2 (9.94 g, 0.102 mole) from a pressurized cylinder.
The pressure of the autoclave was adjusted to 0 psig (101 kPa) with
nitrogen and stirring set at 500 rpm. The contents of the autoclave were
heated to 119-120° C. for 0.5 hour and then vinylidene chloride
was fed to the reactor at a rate of 16 mL per hour for 2 hours (38.7 g,
0.400 mole) at 120° C.; during this time the pressure rose to 43
psig (398 kPa). The vinylidene chloride feed was shut off and the
autoclave held at 120° C. for another 0.5 hour; the final pressure
was 39 psig (370 kPa). The reactor was cooled to ambient temperature and
the bottom layer in the autoclave was discharged via a dip leg (184.7 g);
the discharged solution consisted of a yellow liquid with a small amount
of a dark layer on top.

[0095] The autoclave was then recharged with carbon tetrachloride (198.5
g, 1.29 mole). The autoclave was heated to 120° C. and the
vinylidene chloride feed resumed at 16 mL/hr for 2 hours; the pressure
rose from 29 (301 kPa) to 38 psig (363 kPa). The lower layer was
discharged from the reactor as above to afford 234.8 g of product.

[0096] In the same manner CCl4 was added four more times to the
autoclave (191.4 g, 194.3 g, 201.2, and 192.0 g) with the bottom layer
from the autoclave discharged between additions (232.1 g, 231.9 g, 246.9
g, and 230.6, respectively). The total amount of vinylidene chloride fed
was 2.47 moles. The top layers from the autoclave were combined to give
286.5 g and 2.3 of solid. The overall yield of
1,1,1,3,3,3-hexachloropropane was about 88.5% with a vinylidene chloride
conversion of 85.0%; the overall ratio of 1,1,1,3,3,3-hexachloropropane
to 1,1,1,3,3,5,5,5-octachloropentane was about 21.

[0097] The six bottom layers and the combined top layer from the reactor
were analyzed by a calibrated gas chromatograph. The weights of the
primary solution components are given below.

[0098] Following a procedure similar to Example 3, a 600 mL Hastelloy®
C nickel alloy, mechanically stirred, autoclave was charged with 2.42 g
(0.0180 mole) of CuCl2 and 1.78 g (0.0180 mole) of CuCl. The
autoclave was sealed and then charged with a mixture consisting of
CCl4 (301.0 g, 1.96 moles), propylene carbonate (134.4 g, 1.32
moles), 2-ethyloxazoline (6.91 g, 0.0697 mole) and CH2═CCl2
(9.68 g, 0.0998 mole) from a pressurized cylinder. The pressure of the
autoclave was adjusted to 0 psig (101 kPa) with nitrogen and stirring set
at 500 rpm. The contents of the autoclave were heated to 119-120°
C. for 0.5 hour and then vinylidene chloride was fed to the reactor at a
rate of 16 mL per hour for 2 hours (38.7 g, 0.400 mole) at 120°
C.; during this time the pressure rose to a maximum of 25 psig (274 kPa)
and then dropped to 22 psig (253 kPa). The vinylidene chloride feed was
shut off and the autoclave held at 120° C. for another 0.5 hour;
the final pressure was 21 psig (246 kPa). The reactor was cooled to
ambient temperature and the bottom layer in the autoclave was discharged
via a dip leg (147.7 g); the discharged solution consisted of an amber
liquid with a small amount of a dark layer on top.

[0099] The autoclave was then recharged with carbon tetrachloride (183.3
g, 1.19 mole). The autoclave was heated to 120° C. and the
vinylidene chloride feed resumed at 16 mL/hr for 2 hours; the pressure
rose from 22 (253 kPa) to 29 psig (301 kPa). The lower layer was
discharged from the reactor as above to afford 310.3 g of product.

[0100] In the same manner CCl4 was added four more times to the
autoclave (200.5 g, 197.8 g, 200.3, and 205.8 g) with the bottom layer
from the autoclave discharged between additions (302.5 g, 277.1 g, 261.2
g, and 255.7, respectively). The total amount of vinylidene chloride fed
was 2.50 moles. The top layers from the autoclave were combined to give
144.3 g and 0.3 of solid. The overall yield of
1,1,1,3,3,3-hexachloropropane was about 84.3% with a vinylidene chloride
conversion of 86.1%; the overall ratio of 1,1,1,3,3,3-hexachloropropane
to 1,1,1,3,3,5,5,5-octachloropentane was about 18.

[0101] The six bottom layers and the combined top layer from the reactor
were analyzed by a calibrated gas chromatograph. The weights of the
primary solution components are given below.

[0103] A 400 mL Hastelloy® C nickel alloy shaker tube was charged with
anhydrous cupric chloride (2.18 g, 0.0162 mole), adiponitrile (82.7 g,
0.765 mole), and carbon tetrachloride (133.4 g, 0.867 mole). The tube was
sealed, cooled in a dry ice bath, evacuated, and purged with nitrogen.
The tube was evacuated once more and charged with 12 g (0.43 mole) of
ethylene. The tube was placed in a heating jacket and agitation begun.
The tube was heated to 120-121° C. over the course of 2 hours.
During this time, the pressure rose to 521 psig (3693 kPa) and dropped
steadily to 288 psig (2086 kPa). The tube was allowed to cool overnight
and was vented and purged the next morning. The product was discharged to
afford 224.4 g of a dark red brown liquid layer over an amber lower
liquid layer.

[0104] GC analysis of the layers indicated the following compositions:

[0118] Following a procedure similar to Example 7, a 400 mL Hastelloy®
C nickel alloy shaker tube was charged with anhydrous cupric chloride
(2.18 g, 0.0162 mole), adiponitrile (82.7 g, 0.765 mole),
1,1,1-trichloropentafluoro-propane (102.8 g, 0.433 mole), and vinylidene
chloride (28.0 g, 0.289 mole). The tube was heated to 128-133° C.
over the course of 3.1 h; the pressure dropped from a high of 112 psig
(873 kPa) initially to 72 psig (598 kPa) at the end of the reaction.

[0119] The tube was cooled overnight and vented and purged the next
morning. The product was discharged to afford 205.9 g of a dark red brown
top liquid layer over a dark orange lower liquid layer; some brown
insolubles were observed in the bottom of the jar.

[0120] GC analysis of the layers indicated the following compositions:

[0123] The tube was cooled overnight and vented and purged the next
morning. The product was discharged to afford 212.8 g of a dark red brown
top liquid layer over a almost colorless lower liquid layer.

[0124] GC analysis of the layers indicated the following compositions:

[0130] Following a procedure similar to Example 6, a 400 mL Hastelloy®
C nickel alloy shaker tube was charged with anhydrous cupric chloride
(2.18 g, 0.0162 mole), adiponitrile (82.7 g, 0.765 mole), and
1,1,1-trichlorotrifluoroethane (108.3 g, 0.578 mole). The tube was
sealed, cooled in a dry ice bath, evacuated, and purged with nitrogen.
The tube was evacuated once more and charged with 12 g (0.43 mole) of
ethylene. The tube was placed in the autoclave and agitation begun. The
tube was heated to 129-131° C. over the course of 2 hours. During
this time, the pressure rose to 665 psig (4685 kPa) and dropped steadily
to 564 psig (3989 kPa). The tube was cooled overnight and vented and
purged the next morning. The product was discharged to afford 178.2 g of
a brown liquid layer over an pale yellow lower liquid layer.

[0131] GC analysis of the layers indicated the following compositions:

[0133] Following a procedure similar to Example 6, a 400 mL Hastelloy®
C nickel alloy shaker tube was charged with anhydrous cupric chloride
(2.18 g, 0.0162 mole), adiponitrile (82.7 g, 0.765 mole), and
1-iodoheptafluoropropane (100 g, 0.338 mole). The tube was sealed, cooled
in a dry ice bath, evacuated, and purged with nitrogen. The tube was
evacuated once more and charged with 12.8 g (0.20 mole) of vinylidene
fluoride. The tube was placed in the autoclave and agitation begun. The
tube was heated to 129-130° C. over the course of 4 hours. During
this time, the pressure rose to 366 psig (2624 kPa) and dropped steadily
to 312 psig (2252 kPa).

[0134] The tube was cooled overnight and vented and purged the next
morning. The product was discharged to afford 160.6 g of a brown liquid
layer over an yellow lower liquid layer.

[0135] GC analysis of the layers indicated the following compositions:

[0137] Following a procedure similar to Example 6, a 400 mL Hastelloy®
C nickel alloy shaker tube was charged with anhydrous cupric chloride
(2.18 g, 0.0162 mole), adiponitrile (82.7 g, 0.765 mole), and
1,1,1-trichlorotrifluoroethane (108.3 g, 0.578 mole). The tube was cooled
in dry ice, evacuated, purged with nitrogen, re-evacuated and charged
with vinyl fluoride (10 g, 0.22 mole). The tube was heated to 129-131
° C. over the course of 2.9 hours; during this time the pressure
decreased from 393 psig (2810 kPa) to 304 psig (2197 kPa). The tube was
cooled overnight and vented and purged the next morning. The product was
discharged to afford 178.6 g of a dark red brown top liquid layer over a
pale yellow lower liquid layer.

[0138] GC analysis of the layers indicated the following compositions:

[0140] To a 450 mL Hastelloy® C nickel alloy autoclave provided with an
agitator, condenser operating at -15° C. and a back-pressure
regulator was charged 120 g (0.48 mole) CCl3CH2CCl3
(230fa), prepared by the method of this invention (Examples 1 to 5) and
24 g (0.087 mole) of TaF5. The autoclave was sealed and cooled in
dry-ice. Into the chilled autoclave was condensed 120 g (6.0 moles) of
anhydrous HF. The back-pressure regulator was set to 500 psig (3548 kPa).
The autoclave and contents were brought to room temperature and heated
with stirring at 75° C. (internal temperature) for one hour and at
125°-130° C. for two hours using an electrical heater.
After this period, the autoclave and contents were brought to room
temperature and near atmospheric pressure. A vapor sample was withdrawn
and analyzed by gas chromatography. Area % analysis indicated 96% 236fa
(CF3CH2CF3), 2% 235fa (CF3CH2CF2Cl) and 2%
other products.

[0144] Example 16 was substantially repeated except that the catalyst was
SbCl5 (0.087 mole, 26 g) and the autoclave and contents were
maintained at about 70° C. for two hours before raising the
temperature to 125°-130° C. Analysis indicated 88% 236fa
and 12% 235fa.

Example 19

[0145] CCl3CH2CCl3+HF→CF3CH2CCl2F

[0146] Example 16 was substantially repeated except that the catalyst was
MoCl5 (20 g, 0.087 mole) and the autoclave and contents were
maintained at 80° C. for three hours and the temperature was not
raised any further. Analysis indicated 4% 236fa, 11% 235fa and 76%
CF3CH2CCl2F (234fb) in addition to small amounts of other
products.

Example 20

[0147] CCl3CH2CHCl2+HF→CF3CH2CHF2

[0148] A 160 mL Hastelloy® C nickel alloy Parr reactor equipped with a
magnetically driven agitator, pressure transducer, vapor phase sampling
valve, thermal well, and valve was charged with 10.5 g (0.039 mole)
NbCl5 in a dry box. The autoclave was then removed from the drybox;
50 g (2.5 moles) of HF were added to the autoclave via vacuum transfer.
The autoclave was brought to 14° C. and charged with 10.5 g (0.048
mole) of CCl3CH2CHCl2 (prepared according to the procedure
described in Example 8 above) via a cylinder pressurized with nitrogen.
The autoclave was then heated with stirring; within 19 minutes the
pressure reached 516 psig (3658 kPa) at 120° C. The temperature
was held at 120° C. for 16 minutes. A sample of the reactor vapor
at this point had the following composition:

[0149] In the following two examples, all values for the compounds are in
moles and temperatures are in Celsius. The data were obtained by
calculation using measured and calculated thermodynamic properties. The
numbers at the top of the columns refer to FIG. 1.

[0152] In the following two examples, all values for the compounds are in
moles and temperatures are in Celsius. The data were obtained by
calculation using measured and calculated thermodynamic properties. The
numbers at the top of the columns refer to FIG. 1.

[0155] In the following two examples, all values for the compounds are in
moles and temperatures are in Celsius. The data were obtained by
calculation using measured and calculated thermodynamic properties. The
numbers at the top of the columns refer to FIG. 1.